WTIO30 FMEE 141818
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER: 10/1/20202021
1.A SEVERE TROPICAL STORM 1 (ALICIA)

2.A POSITION 2020/11/14 AT 1800 UTC:
WITHIN 25 NM RADIUS OF POINT 10.2 S / 76.3 E
(TEN DECIMAL TWO DEGREES SOUTH AND
SEVENTY SIX DECIMAL THREE DEGREES EAST)
MOVEMENT: WEST-SOUTH-WEST 12 KT

3.A DVORAK ANALYSIS: 3.5/3.5/S 0.0/12 H

4.A CENTRAL PRESSURE: 992 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 50 KT
RADIUS OF MAXIMUM WINDS (RMW): 37 KM

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 80 SE: 370 SW: 280 NW: 80
34 KT NE: 40 SE: 90 SW: 110 NW: 0
48 KT NE: 0 SE: 60 SW: 60 NW: 0


7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1006 HPA / 700 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS:
12H: 2020/11/15 06 UTC: 12.4 S / 74.5 E, VENT MAX= 060 KT, SEVERE
TROPICAL STORM
24H: 2020/11/15 18 UTC: 14.6 S / 73.7 E, VENT MAX= 070 KT, TROPICAL
CYCLONE
36H: 2020/11/16 06 UTC: 16.4 S / 73.2 E, VENT MAX= 055 KT, SEVERE
TROPICAL STORM
48H: 2020/11/16 18 UTC: 17.5 S / 72.9 E, VENT MAX= 045 KT, MODERATE
TROPICAL STORM
60H: 2020/11/17 06 UTC: 18.5 S / 72.9 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
72H: 2020/11/17 18 UTC: 20.6 S / 72.4 E, VENT MAX= 030 KT, FILLING UP

2.B LONGER-RANGE OUTLOOK:
96H: 2020/11/18 18 UTC: 24.3 S / 71.9 E, VENT MAX= 020 KT, REMNANT
LOW

2.C ADDITIONAL INFORMATION:
T=CI=3.5

OVER THE LAST 6 HOURS, A STRONG CONVECTIVE BURST HAS TRIGGERED NEAR
THE CIRCULATION CENTER. THE 1515Z ASCAT-B SWATH SUGGESTS THAT THE
CIRCULATION CENTER IS LOCATED NEAR THE NORTH-EASTERN BORDER OF THE
CDO, CONFIRMING A SHEARED PATTERN UNDER A WEAK TO MODERATE
EAST-NORTH-EASTERLY UPPER CONSTRAINT. THE ASSOCIATED DVORAK ANALYSIS
IS IN AGREEMENT WITH THE ADT ESTIMATE. CONSISTENTLY, THE ASCAT DATA
SHOW STORM-FORCE WINDS WITHIN THE SOUTHERN SEMI-CIRCLE. THE 89GHZ
1332Z SSMIS IMAGE SHOWS A STILL ILL-DEFINED INTERNAL STRUCTURE, WITH
THE MAIN CONVECTION LIMITED TO THE WESTERN SEMI-CIRCLE.

ALICIA KEEPS ON HEADING SOUTHWESTWARD AT A QUICK PACE ON THE
NORTH-WESTERN SIDE OF THE MID-LEVEL SUBTROPICAL RIDGE. WITH THE
ARRIVAL OFA DEEP TROUGH FROM THE SOUTH-WEST, THE RIDGE SHIFTS
EASTWARD AND WILL LET ALICIA DIVE SOUTHWARD TOMORROW. AVAILABLE
GUIDANCE IS IN GOOD AGREEMENT ON THIS SCENARIO. FROM TUESDAY, THE
UNCERTAINTY IS GREATER WITH TWO POSSIBLE SCENARII : THE PERSISTANCE
OF A SOUTH TO SOUTHEASTWARD MOTION OR THE CAPTURE OF THE REMNANT LOW
BY THE TRADE WINDS.

ENVIRONMENTAL CONDITIONS ARE RATHER CONDUCIVE UNTIL SUNDAY NIGHT,
DESPITE THE WEAK SHEAR CONSTRAINT CURRENTLY AFFECTING THE STORM.
ALICIA SHOULD STILL BENEFIT FROM AN EXCELLENT DIVERGENCE, RELATIVELY
WEAK WIND SHEAR AND A VERY STRONG OCEANIC ENERGY CONTENT. THE SYSTEM
COULD THUS STILL REACH THE TROPICAL CYCLONE STAGE TOMORROW. SUNDAY
NIGHT, CONDITIONS SHOULD BEGIN TO QUICKLY DETERIORATE WITH
INSUFFICIENT SEA TEMPERATURES SOUTH OF 17S, A STRENGTHENING SHEAR
CONSTRAINT, GRADUALLY ASSOCIATED TO MID-LEVEL DRY INTRUSIONS.
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